(a) Field of the Invention
The present invention is related to the design of a touch component for protecting capacitive panel, and more particularly to a design for preventing touch panel from being damaged due to excessive pressure applied.
(b) Description of the Prior Art
The touch panel market based on the physics principle of detecting touch point can be divided into: resistor type whereas the finger or other kind of touch head tips on the panel to create voltage; or the capacitive type whereas the finger is used to attract minute amount of current (usually used on the touch screen panel of notebook PC).
The top layer of the resistive touch panel is a layer of polyester film, the inner side of which has conductive metal coating. The bottom layer of the screen, to be pasted on CRT or LCD screen, is a piece of glass spread with conductive material. Between the glass and the polyester film a layer of minute separating point made of polyester is used for separation. Along the X-axis of the glass plate and the Y-axis of the polyester film there is a controller for each that will apply minute voltage gradient. Whenever the finger or a general-purpose touch pen touches the screen, the two conductive layers will be pressed together and the electronic device could detect the X- and Y-coordinate of the touch point.
In the market in general most touch screen panels are using touch pen to control the screen. However, the said touch pen requires pressing of the point for the control. Therefore, user often will leave a dark damaged mark on the touch panel screen using resistive touch panel technology because of excessive pressure applied. FIG. 1 shows a conventional resistive type touch pen comprising a pen body, one end of the pen body B is a touch pen head B1, wherein the said touch pen is a nonconductive plastic pen but require pressure for conducting operation in order to detect the X- and Y-coordinates of the touch point to achieve the purpose of touch panel control.
The innovative iPhone design presently available in the market is the combination of technology and humanity. Therefore, the circuit used in iPhone is a more complicated capacity touch panel screen. The glass plate of the capacitive touch panel screen has conductive material coated on both sides and outer side is coated with anti-scratch film. The electrodes on the peripheral of glass plate will generate an even, low voltage, electrical field on the outer conductive layer; the inner conductive layer could provide electromagnetic shield and reduce noise. Whenever the finger touches the screen, it will capacitor-couple with the electrical field on the outer conductive layer and attract the minute current. Each electrode is responsible for measuring the current from each corner for the controller to find out the coordinates of the finger. Therefore, comparing the capacitive panel with the older resistive touch panel the said capacitive panel, which could generate capacitor coupling for the detection of touch position through detecting electrical current, as human body is a good conductor, the capacitive panel can only rely on the human body or conductive object to be in touch with the changing current to achieve the result of touch panel.
Therefore, the iPhone products will not be sensitive to conventional touch pen as the conventional touch pen is not conductive and only the conductive skin of the finger can be used for conducting the operation. However, as the area of the finger has larger range, user often might select other items because of the narrow and fine selection items and result in confusion of user's operation. There is still room for improvement for such technology.